Lactam compositions for cleaning organic and plasma etched residues for semiconductor devices

ABSTRACT

A composition for the cleaning of residues from substrates from about 0.01 percent by weight to about 10 percent by weight of one or more fluoride compounds, from about 20 percent by weight to about 50 percent by weight water, from about 20 percent by weight to about 80 percent by weight of an lactam solvent and from 0 to about 50 weight percent of an organic sulfoxide or glycol solvent. The composition has a pH between about 6 and about 10. Additionally, the composition optionally contains corrosion inhibitors, chelating agents, surfactants, acids and bases. In use of the composition, a substrate is contacted with the composition for a time and at a temperature that permits cleaning of the substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a semiaqueous cleaning composition that isparticularly useful for cleaning organic and inorganic compounds or“polymers” (post etch residues) from a semiconductor substrate. As usedherein, the term “semiaqueous” refers to a mixture of water and organicsolvent. The invention also includes methods of using this compositionto clean residues from semiconductor substrates. More particularly, theinvention describes a semiaqueous cleaning composition and processes forits use. The solutions are organoammonium compound and amine carboxylatecompound free and contain fluoride compounds, water, and solvent andoptionally contain corrosion inhibitors, chelating agents, surfactants,acids and bases.

2. Description of Related Art

Fluoride containing chemistries have been used for many years to cleanprime silicon wafers (wafers that have not yet undergone ionimplantation or device construction) in the semiconductor industry.Normally the fluoride chemistry (usually dilute hydrofluoric acid) isused as the last process step in the sequence called “RCA rinses”. Thesubstrate is often contaminated from previous process steps withmonolayer amounts of metal, anions and/or organic contaminants orsurface residues (particles). These contaminants have been shown to havesignificant impact on the electrical integrity of simple test devicestructures and they need to be efficiently cleaned without impairingtheir integrity. Such cleaning methods could include techniquesdiscussed in the technical literature, for example, Int. Conf. On SolidState Devices and Materials, 1991, pp. 484-486 or Kujime, T. et al.,Proc. of the 1996 Semi. Pure Water and Chemicals, pp. 245-256 andSinger, P. Semi. International, p.88, October 1995.

Patents that teach methods for cleaning prime wafers with low pHsolutions include U.S. Pat. Nos. 5,560,857 and 5,645,737; 5,181,985;5,603,849; 5,705,089.

Using fluoride chemistries (usually HF) as a final RCA cleaning stepwill cause the silicon wafer surface to be in a hydrophobic state (thesurface is covered with Si—H groups) which will repel water. During thiscleaning step a certain proportion of the wafer surface is dissolved(removed). Unless the cleaning conditions are carefully monitored (time,temperature, solution composition) the substrates can be damaged, asreported by Rafols, C. et al., J Electroanalytic Chem. 433, pp. 77-83,1997. Numerous compositions combine water and organic solvents. Thewater concentration in these HF solutions is very critical. Silica oxidehas an etch rate of 21 Å/min (@ 25° C.) in HF/water, but in isobutanolthe rate was reduced to 2.14 Å/min and even lower in acetone (an aproticsolvent) the rate was only 0.12 Å/min, as reported at NSF/SRC Eng. Res.Center, Environmentally Benign Semiconductor Manufacturing, Aug. 5-7,1998, Stanford University.

After the Front End of Line (FEOL) cleaning process the wafer proceedsto the typical Back End of Line (BEOL) manufacturing process for asemiconductor devices, in which the devices might be dynamic randomaccess memories (DRAMs), static random access memories (SRAMs), logic,electrically programmable read only memories (EPROMs), complementarymetal on silicon (CMOS), and the like. Etching fabrication technologyusing chemical reactions (liquid or plasma) has been used as a method offorming a wiring structure on such semiconductor substrates.

A photoresist film is deposited on the wafer to form a mask, then asubstrate design is imaged on the film layer, baked, and the undevelopedimage is removed with a photoresist cleaner. The remaining image is thentransferred to the underlying material (either a dielectric or metal)with reactive etching gases promoted with plasma energy. The etchantgases selectively attack the unprotected area of the substrate. Liquidetching chemistries, usually containing fluoride chemistries have beenused extensively over the years to etch metals (Al) and dielectrics. Thefluoride chemistries can be very aggressive and can result in isotropicetching (etching equally in all directions). Isotropic etching effectscannot be tolerated with today's needs for tight critical dimensioncontrol, though there have been attempts to control the isotropic etchthrough statistical process control techniques, as reported by Taylor,D., Solid State Technology, July 1998, p. 119.

The usual plasma etching process involves anisotropic (unidirectional)etching while at the same time the byproducts (composed of photoresist,etching gasses and etched materials) are deposited on the sidewall ofetched openings as residues.

A disadvantage of forming this protective sidewall deposit is that itcan be very difficult to remove the residue after the etching procedure.If the components in these residues are not removed or neutralized insome manner then the residues will absorb moisture and form acidicspecies that can corrode the metal structures. The resultant acidcorrodes wiring materials to bring about an adverse effect such as anincrease in electrical resistance and wire disconnection.

Such problems frequently occur, in particular in aluminum and aluminumalloys generally used as wiring material. The wafer substrate in contactwith acidic materials, if not controlled, can destroy the metalstructures.

Following completion of the etching operation it is necessary that theresist mask be removed from the protective surface to permit finishingoperations. It is desirable to develop an improved cleaning compositionto remove the organic polymeric substance from a coated inorganicsubstrate without corroding, dissolving or dulling the metal circuitryor chemically altering the wafer substrate.

Cleaning compositions used for removing photoresist coatings if notalready ashed and other substrates have for the most part been highlyflammable, generally hazardous to both humans and the environment, andcomprise reactive solvent mixtures exhibiting an undesirable degree oftoxicity. Moreover, these cleaning compositions are not only toxic, buttheir disposal is costly since they might have to be disposed of as ahazardous waste. In addition, these compositions generally have severelylimited bath life and, for the most part, are not recyclable orreusable.

Side wall residues have been removed with either acidic organic solventsor alkaline organic solvents. The acidic solvents are generally composedof phenolic compounds or chloro-solvent and/or an aromatic hydrocarbonand/or alkylbenzenesulfonic acids. These formulations generally need tobe used at temperatures up to and beyond 100° C. These chemistriesnormally need to be rinsed with isopropanol.

Dilute hydrofluoric acid solutions can under certain conditions removethe sidewall polymers by aggressively attacking the via sidewall of thedielectric and therefore changing the dimensions of the device, astaught by Ireland, P., Thin Solid Films, 304, pp. 1-12 (1997), andpossibly the dielectric constant. Previous chemistries that contain HF,nitric acid, water and hydroxylamine are aggressive enough to etchsilicon, as taught by U.S. Pat. No. 3,592,773 issued to A. Muller.Recent information also indicates that the dilute HF solutions can beineffective for cleaning the newer CF, etch residues, as taught by K.Ueno et al., “Cleaning of CHF₃ Plasma-Etched SiO₂/SiN/Cu Via Structureswith Dilute Hydrofluoric Acid Solutions,” J. Electrochem. Soc., vol.144, (7) 1997. Contact holes opened on to the TiSi₂ have also beendifficult to clean with HF solutions since there appears to be an attackof the underlying TiSi₂ layer. There may also be difficulty with masstransport of the chemicals in the narrow hydrophilic contact holes, astaught by Baklanov, M. R. et al., Proc. Electrochem. Soc., 1998, 97-35,pp. 602-609.

The photoresist around the contact hole of common interlayerdielectrics, TEOS (tetraethylorthosilicate) and boron phosphosilicateglass (BPSG), which are commonly used in ultra large scale integration(ULSI) structures for better conformity of step coverage, is usuallyremoved with HF solutions. It is not uncommon for the HF to also attackthe dielectric material. Such attack is not desirable (see Lee, C. andLee, S, Solid State Electronics, 4, pp 921-923 (1997)).

The alkaline organic solvents for post etch residue removal can becomposed of amines and/or alkanolamines and/or neutral organic solvents.These formulations generally must be used at temperatures above 100C.Recently a new class of post etch residue cleaning chemistries has beenused to clean these substrates. These chemistries include hydroxylamine,amines, alkanolamines and corrosion inhibitors and generally operate attemperatures 20 to 30 degrees lower.

Recently, fluoride-based chemistries have been used in limited cases toremove post etch residues and to a limited extent, photoresist residuesfrom integrated circuit substrates during BEOL (Back End of Line)processes. Many of the wafer cleaning compositions contain fluoridecomponents, specifically hydrogen fluoride. In addition thesecompositions might contain strong caustic chemicals(choline-derivatives, tetraalkyl ammonium hydroxide, ammonium hydroxide)such as disclosed in U.S. Pat. No. 5,129,955; U.S. Pat. No. 5,563,119;or U.S. Pat. No. 5,571,447, or might use a two-phase solvent system,which contains one phase with hydrofluoric acid and water while a secondphase contains a nonpolar organic solvent (ketones, ethers, alkanes oralkenes) (U.S. Pat. No. 5,603,849). Other formulations includehydroxylamine and ammonium fluoride (U.S. Pat. No. 5,709,756, issued toWard). Additional examples include quaternary ammonium salt and fluoridebased compositions, as disclosed in published European Application662705, and organocarboxylic ammonium salt or amine carboxylate andfluoride based compositions, as disclosed in U.S. Pat. No. 5,630,904.

Some chemistries have also included chelating agents to help removeionic and anionic contamination from the wafer surface (PCT US98/02794)but chelating agents such as citric acid, gallic acid, and catecholamong others, can be aggressive toward the aluminum oxide that coversthe Al metal lines. Studies by Ohman and Sjoberg show that the strongcomplexing ability of citric ions can increase the aluminum oxidesolubility and thereby expose the metal to further corrosion, by factorsof 166 and 468 at pH 5 and 6 (see Ohrnan et al., J. Chem. Soc., DaltonTrans. (1983), p. 2513).

Other methods for cleaning metal and metal oxide residues on wafersinclude spraying water vapor into the plasma ashing chamber followed byintroducing fluorine containing gases (hydrofluoric acid) (U.S. Pat. No.5,181,985) or a liquid containing hydrofluoric acid, ammonium fluorideand water with a pH between 1.5 to less than 7.

There is also a need to remove particulate residues from the wafersurfaces during the BEOL process. Currently most processes rely on anisopropanol and/or DI water rinse with/or without ultra- or megasoniccleaning. For post chemical mechanical polishing (CMP) cleaning of oxidewafers, normally only DI water is used, but with tungsten wafers acombination of dilute NH₄OH and dilute HF usually are required

There are five mechanisms for removing impurities particles and/or ions)from the wafer surfaces:

1. Physical desorption by solvents, which involves replacing a smallnumber of strongly absorbed particles with a large volume of weaklyadsorbed solvent (changing the interaction of the surface charges);

2. Change the surface charge with either acids or bases, i.e. the Si—OHgroup can be made positive or protonated with acid or made negative withbases by removing the proton;

3. Ion complexion by removing adsorbed metal ions by adding acid (i.e.ion exchange);

4. Oxidation or decomposition of impurities, which involves oxidation ofmetals, organic materials or the surface of slurry particles, willchange the chemical forces between the impurities and substrate surface.The chemical reaction can either be through redox chemistry or freeradicals;

5. Etching the oxide surface, which releases the impurity whiledissolving a certain thickness of the substrate surface.

Currently available fluoride-based chemistries can help in items #2 and5, but the cleaning conditions must be carefully controlled. In manycases, the components of the cleaning compositions are relatively toxicreactive solvent mixtures and thus must be subject to stringent useconditions and require hazardous chemical handling procedures andwearing of safety garments and apparel by users so as to avoid contactwith the cleaning compositions. Additionally, because many of the toxiccomponents of such cleaning compositions are highly volatile and subjectto high evaporation rates, they require special human and environmentalsafety precautions to be taken during storage and use of thecompositions.

Accordingly, there exists a need to develop improved cleaningcompositions to efficiently clean a variety of deposits from a widevariety of substrates. Particularly in the field of integrated circuitfabrication, it should be recognized that the demands for improvedcleaning performance with avoidance of attack on the substrates beingcleaned are constantly increasing. This means that compositions thatwere suitable for cleaning less sophisticated integrated circuitsubstrates may not be able to produce satisfactory results withsubstrates containing more advanced integrated circuits in the processof fabrication.

These compositions should also be economical, environmental friendly andeasy to use.

The present invention teaches such a new and improved cleaningcomposition and a process for its use. This composition is aqueous,dissolves both organic and inorganic substances, and, when used in theprocess, is able to clean a variety of substrates. The compositionprovides a more effective cleaning of the substrates, which means moreeffective residue removal, which in turn means that higher productyields can be obtained from the substrates being cleaned.

SUMMARY OF THE INVENTION

The novel cleaning compositions of the invention exhibit synergisticallyenhanced cleaning action and cleaning capabilities at low temperaturesthat are not possible from the use of the individual components, or thecomponents in combination with other cleaning components, or thecomponents in combination with other cleaning components such asethoxyethanolamine or alkylamides.

It is a general object of the invention to provide a semiconductorsubstrate cleaning composition that is effective at low temperatures.

It is a further object of the invention to provide a post etch residuecleaning composition that inhibits redeposition of metal ions.

It is a further object of the invention to form such a cleaning solutionthat is not flammable.

It is a further object of the invention to provide such a cleaningsolution having low etch rates of silicon oxide.

It is a further object of the invention to provide such a cleaningsolution and a process which removes post etch residues from metalstructures.

It is a further object of the invention to provide such a cleaningsolution and a process which removes post etch residues from vias.

It is a further object of the invention to provide such a cleaningsolution and a process which removes post etch residues from low kdielectrics.

These and related objects are attained through the use of thecomposition and process disclosed herein.

A composition in accordance with this invention is for the cleaning ofresidues from substrates and is organoammonium and amine carboxylatefree. It comprises from about 0.01 percent by weight to about 10 percentby weight of one or more fluoride compounds, from about 20 percent byweight to about 50 percent by weight water, from about 20 percent byweight to about 80 percent by weight of a lactam solvent and from 0 toabout 50 weight percent of an organic sulfoxide or glycol solvent. Thecomposition has a pH between about 6 and about 10. Additionally, thecomposition optionally contains corrosion inhibitors, chelating agents,surfactants, acids and bases.

A process for cleaning residue from a substrate in accordance with thisinvention comprises contacting the substrate with an organoammonium andamine carboxylate free composition comprising one or more fluoridecompounds, water and lactam solvent at a temperature and for a timesufficient to clean the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are triangle diagrams plotting cleaning results achievedin practice of the invention as a function of composition.

FIGS. 3 and 4 are triangle diagrams plotting corrosion results achievedin practice of the invention as a function of composition.

FIG. 5 is a triangle diagram plotting pH as a function of compositionsin accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

The cleaning composition of this invention is organoammonium and aminecarboxylate free. Several advantages are achievable by being able toeliminate organoammonium and amine carboxylate compounds from thecompositions. Eliminating these compounds reduces cost of the product.Organoammonium and amine carboxylate compounds are also a class ofcompound called phase transfer catalysts. Such compounds under certainsolvent conditions can accelerate undesirable side reactions; i.e.activation of hydroxide or halide reactions (which can corrode metalsurfaces), as reported by “Phase-Transfer Catalysis in Industry,” APractical Guide and Handbook; March 1991, PTC Interface, Inc. Marietta,Ga. The presence of these compounds in the chemistries can alsointroduce additional cationic and anionic contamination as raw materialsources.

The cleaning composition contains one or more fluoride compounds.Suitable fluoride compounds are ammonium fluoride, ammonium bifluorideand hydrogen fluoride. The preferred fluoride compounds are ammoniumfluoride and ammonium bifluoride. If hydrogen fluoride is employed, abuffer may be required to bring the pH between about 6 and about 10. Thefluoride compounds are desirably present in an amount of from about 0.01percent by weight to about 10 weight percent, preferably from about 0.05weight percent to about 5 weight percent. In general, the lower theconcentration of the fluoride compound in the composition, the higherthe temperature of use needs to be.

The cleaning composition contains one or more lactam solvents. Suitablelactam solvents include lactams having from 4 to 7 membered rings,including 1 to 5 carbon atom alkyl and alkoxy substituted lactams and 5to 7 member ring alkane substituted lactams. Suitable specific examplesof lactam solvents include piperidones, such as 1 to 5 carbon atomalkyl, dialkyl and alkoxy, dialkoxy piperidones, including N-methylpiperidone, dimethyl piperidone, N-methoxy piperidone, dimethoxypiperidone, N-ethyl piperidone, diethylpiperidone, diexthoxy piperidone,and the like; cyclohexyl analogues of these piperidones, such asN-methyl pyrrolidone, N-2(hydroxyethyl-2-pyrrolidone,N-2(cyclohexyl)-2-pyrrolidone, and the like. The preferred lactamsolvents are N-methyl piperidone, dimethyl piperidone and N-methylpyrrolidone. Dimethyl piperidone is commercially available as a mixtureof predominantly 1,3 dimethyl piperidone and a minor amount of 1,5dimethyl piperidone. The lactam solvents can be used either singly or asmixtures. The composition optionally contains alkyl sulfoxides such asdimethyl sulfoxide and/or glycols, such as propylene glycol.

The cleaning composition contains water. Typically high-purity deionizedwater is used.

The composition optionally contains corrosion inhibitors. Suitablecorrosion inhibitors include inorganic nitrate salts such as ammonium,potassium, sodium and rubidium nitrate salts, aluminum nitrate and zincnitrate.

The composition optionally contains chelating agents. Suitable chelatingagents are described in commonly assigned U.S. Pat. No. 5,672,577,issued Sep. 30, 1997 to Lee, which is incorporated herein by reference.Preferred chelating agents include catechol, ethylenediaminetetraaceticacid, citric acid, pentandione and pentandione dioxime.

The composition optionally contains surfactants. Suitable surfactantsinclude poly(vinyl alcohol), poly(ethyleneimine) and any of thesurfactant compositions classified as anionic, cationic, nonionic,amphoteric, and silicone based. Preferred surfactants are poly(vinylalcohol) and poly(ethyleneimine).

Some combinations of components require the addition of acids and/orbases to adjust the pH to an acceptable value. The acids suitable foruse in the present invention are organic or inorganic. The acids caninclude nitric, sulfuric, phosphoric, hydrochloric acids (thoughhydrochloric acid can be corrosive to metals) and the organic acids,formic, acetic, propionic, n-butyric, isobutyric, benzoic, ascorbic,gluconic, malic, malonic, oxalic, succinic, tartaric, citric, gallic.The last five organic acids are examples of chelating agents.

 X=—OH, —NHR, —H, —Halogen, —CO₂H and —CH₂—CO₂H, —CHOH—CO₂H

R=generally aliphatic, H or aromatic

Concentrations of the acids can vary from about 1 to about 25 wtpercent. The important factor is the solubility of the acid and baseproducts with any additional agents in the aqueous solutions.

The caustic components suitable for use to adjust the pH of the cleaningsolution can be composed of any common base, i.e. sodium, potassium,magnesium hydroxides, or the like. The major problem is that these basesintroduce mobile ions into the final formulation. Mobile ions coulddestroy computer chips being produced today in the semiconductorindustry. Other bases can include choline (a quaternary amine) orammonium hydroxide.

Operation

The method of cleaning a substrate using the cleaning compositions ofthe present invention involves contacting a substrate having residuethereon, particularly organometallic or metal oxide residue, with acleaning composition of the present invention for a time and at atemperature sufficient to remove the residue. Stirring, agitation,circulation, sonication or other techniques as are known in the artoptionally may be used. The substrate is generally immersed in thecleaning composition. The time and temperature are determined based onthe particular material being removed from a substrate. Generally, thetemperature is in the range of from about ambient or room temperature to100° C. and the contact time is from about 30 seconds to 60 minutes. Thepreferred temperature and time of contact for this invention is 20 to45° C. from 2 to 60 minutes. Generally the substrate will be rinsedafter using the composition. Preferred rinse solutions are isopropanoland DI water.

The compositions of the invention are particularly useful for removingresidue from metal and via features. The compositions of the inventionare particularly useful on low-k dielectrics. Low-k dielectrics areknown in the art and include fluorinated silicate glass (FSG), hydridoorgano siloxane polymer (HOSP), low organic siloxane polymer (LOSP),nanoporous silica (Nanoglass), hydrogen silsesquioxane (HSQ), methylsilsesquioxane (MSQ), divinysiloxane bis(benzocyclobutene) (BCB), silicalow-k (SiLK), poly(arylene ether) (PAE, Flare, Parylene), andfluorinated polyimide (FPI).

Examples of cleaning compositions and processes according to the presentinvention suitable for removing resist mask or residues from a substrateare set forth in examples below.

EXAMPLE 1

A group of cleaning chemistries containing the ingredients of ammoniumfluoride, water, and one of dimethyl piperidone, acetonitrile andhydroxylarnine were tested with metal wafers which have stacks ofTEOS/Ti/TiN/AlCu/TiN (from Bottom to Top) etched with CL₂/BCl₃ plasma ina commercially available AMT DPS etcher. The resulting metal wafers withresidues were cut into small sample pieces, and then the sample pieceswere immersed into the chemistry solutions in Table 1 for cleaning for 5minutes at room temperature. The sample pieces were taken out, rinsedwith deionized water and dried with the flow of N₂. SEM was performedwith a Hitachi 4500 FE-SEM for evaluating cleaning and corrosioneffects. Residue removal and corrosion effects on metal stack wereassessed by visual comparisons and were all ranked on a scale of 1 to10. The formulations in table 1 are shown in weight percent.

TABLE 1 DI Time Metal Lines Formula NH₄F water ACN DMP HDA (Min.) CleanAl Ti TiN Oxide A 1 35 64 5 10 7 10 10 10 B 1 35 64 5 10 8 10 10 10 C 135 64 5  8 10  10 10 10 Reaction Temperature: Room Temperature DI water:Deionized water ACN: Acetonitrile DMP: 1,3-Dimethylpiperidone HDA:Hydroxylamine Metal Retention for Metal Lines Clean lines: 1 - poor 10 -complete Al retention: 10 - no change, 1 - Metal undercut Ti retention:10 - no change, <5 - see attack TiN retention: 10 - no change, <5 - seeattack Oxide retention: 10 - no change, <5 - see attack

The results showed that the DMP containing formulation gave thecombination of the best cleaning performance with the smallest extent ofcorrosion, in the form of a slight attack on aluminum. On this basis,DMP was chosen for further study to provide an enhanced formulation.

EXAMPLE 2

Based on the results in Example 1, formulations with low ammoniumfluoride concentrations were evaluated to determine a lower limit forthe ammonium fluoride in the cleaning formulations with ammoniumfluoride and water and DMP. A commercially available LAM TCP9600 etcherwith a Cl₁/BCl₃ plasma was used for etching metal wafers with a stack ofOxide/Ti/TiN/AlCu/TiN (from bottom to top). The resulting metal waferswith residues were cut into small sample pieces, and the sample pieceswere immersed into the cleaning solutions in Table 2 for cleaning for 5minutes at room temperature. The sample pieces were taken out, rinsedwith deionized water and dried with a flow of N₂. SEM was performed witha Hitachi 4500 FE-SEM for evaluating cleaning and corrosion effects.Residue removal and corrosion effects on the metal stack were assessedby visual comparisons and were all ranked on a scale of 1 to 10. Theformulations in table 2 are shown in weight percent.

TABLE 2 DI Time Metal Lines Formula NH₄F water DMP (Min.) Clean Al TiTiN Oxide D 0   31   69 5 1 10 10 10 10 E  0.08  30.92 69 5 7 10 10 1010 F  0.12  30.88 69 5 6 10 10 10 10 G  0.14  30.86 69 2 7 10 10 10 10 H0.2 40.8 59 2 7   8.5 10 10 10 I 0.2 20.8 79 2 10  10 10 10 10 J 0.225.8 74 2   9.5 10 10 10 10 K 0.2 30.8 69 2 9 10 10 10 10 ReactionTemperature: Room Temperature DI water: Deionited water DMP:1,3-Dimethylpiperidone Metal Retention for Metal Lines Clean lines: 1 -poor 10 - complete Al retention: 10 - no change, 1 - metal undercut Tiretention: 10 - no change, <5 - see attack TiN retention: 10 - nochange, <5 - see attack Oxide retention: 10 - no change <5 - see attack

These results show that significant cleaning results are obtained withcompositions containing as little as about 0.1 weight percent of theammonium fluoride, with no corrosion. Better cleaning results in ashorter treatment time are obtained with an ammonium fluorideconcentration of 0.2 weight percent in the formulations.

EXAMPLE 3

The procedure of Example 2 was repeated with formulations containing 0.3weight percent or 1.0 weight percent of ammonium fluoride and withpropylene glycol added as an additional solvent. The results are shownin Tables 3 and 4.

TABLE 3 Formulation in wt. % DI Time Metal Lines Formula NH₄F water DMPPG (Min.) Clean Al Ti TiN Oxide LL 0.3 49.7 10 40 5 8  6 10 10 10 MM 0.359.7 20 20 5   9.5  5 10 10 10 NN 0.3 49.7 40 10 5   8.5  4 10 10 10 OO0.3 79.7 10 10 5 9  7 10 10 10 PP 0.3 79.7 30 30 5 8 10 10 10 10 QQ 0.339.7 24 48 5 10  10 10 10 10 RR 0.3 27.7 67  5 5 10  10 10 10 10 SS 0.327.7 57 15 5 10  10 10 10 10 TT 0.3 27.7  0 70 5 1 10 10 10 10 UU 0.329.7 45 25 5 7 10 10 10 10 VV 0.3 29.7 25 45 5 7 10 10 10 10 WW 0.3 29.769  0 5 1 10 10 10 10 XX 0.3 30.7 35 35 5 7 10 10 10 10 ReactionTemperature: Room Temperature DI water: Deionized water DMP:1,3-Dimethylpiperidone PG: Propylene glycol Metal Retention for MetalLines Clean lines: 10 - complete, 1 - not clean at all Al retention:10 - no change, 1 - Al layer gone Ti retention: 10 - no change, 1 - Tilayer gone TiN retention: 10 - no change, 1 - TiN layer gone Oxideretention: 10 - no change, 1 - Oxide layer gone

TABLE 4 Formulation in wt. % DI Time Metal Lines Formula NH₄F water DMPPG (Min.) Clean Al Ti TiN Oxide L 1 49 10 40 5 8  7 10 10 10 M 1 59 2020 5 10   6 10 10 10 N 1 49 40 10 5 7  7 10 10 10 O 1 79 10 10 5 8  3 1010 10 P 1 39 30 30 5 7 10 10 10 10 Q 1 27 24 48 5 10  10 10 10 10 R 1 2767  5 5   9.5   9.5 10 10 10 S 1 27 57 15 5 10  10 10 10 10 T 1 29  0 705 8 10 10 10 10 U 1 29 45 25 5 10  10 10 10 10 V 1 29 25 45 5 8 10 10 1010 W 1 30 69  0 5 10   7 10 10 10 X 1 29 35 35 5   8.5 10 10 10 10Reaction Temperature: Room Temperature DI water: Deionized water DMP:1,3-Dimethylpiperidone PG: Propylene glycol Metal Retention for MetalLines Clean lines: 10 - complete, 1 - not clean at all Al retention:10 - no change, 1 - Al layer gone Ti retention: 10 - no change, 1 - Tilayer gone TiN retention: 10 - no change, 1 - TiN layer gone Oxideretention: 10 - no change, 1 - Oxide layer gone

In order to understand the results obtained with the formulations shownin Tables 3 and 4, the data was plotted in the four triangle diagrams ofFIGS. 1-4, showing respectively, residue cleaning performance as afunction of water, DMP and PG concentration in the low fluoride and highfluoride solutions, and aluminum corrosion as a function of water, DMPand PG concentration in the low fluoride and high fluoride solutions.FIG. 5 shows pH of the Table 3 compositions as a function of water, DMPand PG concentration in the solutions. The pH values as reported in FIG.5 were measured with an Orion SA520 meter with glass pH electrode. Acomparison of FIG. 1 with FIG. 2 shows that higher fluorideconcentrations are sometimes necessary to obtain satisfactory cleaningresults with high water and high DMP concentrations. FIGS. 3 and 4 showthat the least corrosion occurs with a high concentration of DMPrelative to water. FIG. 5 in combination with FIGS. 1-4 shows theappropriate pH range for avoiding substantial aluminum corrosion andobtaining optimum cleaning results.

EXAMPLE 4

As a result of the above experimental work, an especially preferredcomposition was determined to be 0.75 % of 40% concentration by weightin water ammonium fluoride, 17% by weight DMSO (dimethyl sulfoxide),57.25 % by weight DMP (dimethyl piperidone) and 25 % by weight D.I.Water. Further tests in accordance with the procedure of Example 2 gavecorrosion numbers of 10 and cleaning numbers of 10 for all of thesubstrate materials listed in Tables 3 and 4.

Substitution of other fluorine compounds, lactam solvents, organicsulfoxides and other glycols gives similar advantageous results.

One skilled in the art will recognize from the foregoing examples thatmodifications and variations can, and are expected to be made, to theforegoing cleaning solution in accordance with varying conditionsinherent in the production process. The embodiments above are given byway of example. For example, the specific discussion of dielectricpreservation is indicative of other metal, metal alloy, and polysiliconstructures protected by the proposed cleaning solution and method. Theteaching examples do not limit the present invention, which is definedby the following claims.

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The invention now being fully described, it will be apparent to one ofordinary skill in the art that many changes and modifications can bemade thereto without departing from the spirit or scope of the appendedclaims.

What is claimed is:
 1. An organoammonium and amine carboxylate freecomposition for the cleaning of residues from substrates, comprisingfrom about 0.01 percent by weight to about 10 percent by weight of oneor more fluoride compounds, from about 20 percent by weight to about 50percent by weight water, from about 20 percent by weight to about 80percent by weight of a piperidone and from 0 to about 50 weight percentof an organic sulfoxide or glycol solvent, said composition having a pHbetween about 6 and about
 10. 2. The composition of claim 1 in which thepiperidone is a 1 to 5 carbon atom alkyl or alkoxy substitutedpiperidone or a 5 to 7 member ring alkane substituted piperidone.
 3. Thecomposition of claim 2 in which the piperidone is a 1 to 5 carbon atomalkyl, dialkyl alkoxy or dialkoxy piperidone.
 4. The composition ofclaim 3 in which the piperidone is N-methyl piperidone, dimethylpiperidone, N-methoxy piperidone, dimethoxy piperidone, N-ethylpiperidone, diethylpiperidone or diexthoxy piperidone.
 5. Thecomposition of claim 2 in which the lactam is dimethyl piperidone. 6.The composition of claim 2 in which the fluoride compound is ammoniumfluoride, ammonium bifluoride or hydrogen fluoride.
 7. The compositionof claim 1 in which the fluoride compound is ammonium fluoride, ammoniumbifluoride or hydrogen fluoride.
 8. The composition of claim 1 furthercomprising a corrosion inhibitor.
 9. The composition of claim 1 furthercomprising a chelating agent.
 10. The composition of claim 1 furthercomprising a surfactant.
 11. The composition of claim 1 furthercomprising an acid.
 12. The composition of claim 1 further comprising abase.
 13. The composition of claim 5 in which the fluoride compound isammonium fluoride.
 14. The composition of claim 13 further comprisingdimethyl sulfoxide or propylene glycol.
 15. A process for cleaningresidue from a substrate, which comprises contacting the substrate withan organoammonium and amine carboxylate free composition comprising fromabout 0.01 percent by weight to about 10 percent by weight of one ormore fluoride compounds, from about 20 percent by weight to about 50percent by weight water, from about 20 percetn by weight to about 80percent by weight of piperidone and from 0 to about 50 weight percent ofan organic sulfoxide or glycol solvent at a temperature and for a timesufficient to clean the substrate.
 16. The process of claim 15 in whichthe temperature is from about 20° to about 100° C.
 17. The process ofclaim 16 where the temperature is about 20° to about 45° C.
 18. Theprocess of claim 16 in which the time is from about 3 minutes to about10 minutes.
 19. The process of claim 15 in which the composition has apH between about 6 and about
 10. 20. The process of claim 19 in whichthe composition additionally comprises from about 0.01 weight percent upto about 50 weight percent of an organic sulfoxide or glycol solvent.21. The composition of claim 1 in which the piperidone is a compoundfrom the group consisting of N-methyl piperidone and dimethylpiperidone.